This invention relates to a process for preparing a composition comprising a tin dioxide-coated porous ceramic support material and noble metal promoter(s), said composition being effective as a catalyst for the oxidation of carbon monoxide with free oxygen to carbon dioxide.
Catalyst compositions comprising a SnO.sub.2 -coated ceramic support material and promoters (such as Pd, Pt, Mn and Cr) are well known, and have been described in U.S. Pat. Nos. 4,524,051 and 4,830,844. The catalyst support material is generally prepared by dipping a ceramic material (preferably a monolith) into a colloidal dispersion of hydrated tin dioxide, followed by drying and calcining. This method requires the preparation of a colloidal dispersion of hydrated tin dioxide by a tedious, multi-step procedure, as has been described in the above-cited U.S. patents. The present invention is directed to a simplified method of preparing a SnO.sub.2 -coated porous ceramic material to be used as a support material for CO oxidation catalysts.